For most of the year, their lichen-packed diets are pretty different from ours, but when mushrooms season rolls around in the summer, both reindeer and humans love to sample the local fungi fare. Though we've come a long way since the Chernobyl nuclear power plant left a radioactive catastrophe in its wake, today (nearly 30 years later) Norway's grazing animals still test positive for radioactive contamination ... and researchers suspect their favourite fungi are to blame.

Rozites caperatus is among the edible fungi that can take up most radioactive cesium from the soil. Image: Giorgio___/Flickr

"While the overall level of Chernobyl contamination in plants and animals has fallen, there is still much radioactivity bound in the soil," explains Lavrans Skuterud, a researcher at The Norwegian Radiation Protection Authority. Along with his team and colleagues at the Norwegian Food Safety Autority, Skuterud works to monitor how much of the radioactive isotope cesium-137 is transferred to reindeer, to ensure local communities can trade their meat. 

Fungi are particularly good at absorbing radioactive elements from the soil they grow in, and after what Skuterud describes as an exceptionally wonderful Norwegian summer, contamination levels in the nation's reindeer have reached alarming highs. 

"The maximum values are the highest observed since 1998 – that is the biggest surprise," says Skuterud. "The reason for this is probably a combination of the length of the fungi season (the animals have been eating fungi over several weeks) and the composition of fungi species," he says. "Rozites caperatus does not fruit every year, but this year extreme amounts have been reported from many locations – and this species is among the edible fungi that can take up most radioactive caesium from the soil."

Two years ago, the most radioactive reindeer tested in the region of Vågå contained 1,500 becquerels per kilogram (Bq/kg) of cesium-137. This year, a number of reindeer from the same location topped the charts at 8,200. According to Skuterud, the consensus is that people should not be ingest more than a total of 80,000 Bq/kg per year and generally should not ingest food containing concentrations over 600 Bq/kg. 

Lavrans Skuterud monitors a reindeer calf in Vågå. Image: NRPA/Skuterud

"The permissible level of radioactive cesium in traded reindeer meat in Norway is 3,000 Bq/kg," explains Skuterud, adding that this high level was chosen to reduce the cultural consequences for the indigenous people who live by herding. "They were in danger of losing their livelihood. That could have led to more serious health problems than the radioactivity in the meat they sell," he says.

It's important to note that this spike (though unexpected and very abnormal) is not cause for a radiation-related panic attack. Skuterud and his team believe the numbers will fall in winter, as they have observed in previous years ... but for those who rely on reindeer herding to survive, there is little comfort in this.

While sheep farmers have the option to pen and 'clean feed' their livestock (which allows decontamination), animal welfare concerns prevent reindeer herders from doing the same. Having sent over 800 animals back to pasture already, they have no choice but to sit back and wait for their only source of income to become safe for consumption and sale once again.

"Our concerns are for the animal owners – and for how long we will be dealing with the consequences of the Chernobyl accident that happened nearly 30 years ago," says Skuterud."We are therefore again working on our remediation strategies, to see if they can be improved in a way that makes the situation more predictable for the owners."

A reindeer herder in Vågå. Image: Skuterud

Top header image: Lavrans Skuterud